The present invention relates to devices for green machining bevel gears, in particular devices which are designed for dry machining. The present invention also relates to a corresponding method.
There are greatly varying machine tools which are used in the manufacture of bevel gears and similar gears. For some time, there has been a wish for automating the manufacture. One solution, which has only been able to succeed in a limited way up to this point, however, is a machining center which is designed so that a large number of manufacturing steps may be executed on the same machine tool. Such machine tools are not only very complex and therefore costly, but rather also require relatively great effort in the preparatory set up (equipping time). On the other hand, such machine tools, which have been developed in regard to high flexibility, are more suitable for producing individual fabrications or extremely small series.
A compact machine tool which is designed for turning and hobbing a workpiece is shown and described in European Patent EP 0 832 716 B1, this workpiece not having to be rechucked or transferred. In other words, the workpiece is seated on a main spindle after the chucking and is machined there using various tools. It is seen as a disadvantage of this machine tool that, because of the configuration of the various elements, it is not designed for the purpose of executing dry machining, because the removal of the hot chips is of special significance during dry machining. In addition, the movement clearance is restricted by the lateral configuration of the two carriages having the tools in relation to the workpiece. The machine tool shown is not capable of machining bevel gears, ring gears, or the like, but rather is conceived for machining spur gears.
A further machine tool is known from Published Application DE 199 18 289 A1, in which two steps are executed in sequence without having to rechuck the workpiece. The first step executed on this machine tool is rough machining of a spur gear using a hobbing cutter, to give the workpiece a coarse contour and surface. A fine machining method then follows, the workpiece also remaining in the same chucking for this purpose.
It is seen as a disadvantage of the machine tools which machine a workpiece in multiple steps without rechucking the workpiece that a large number of different parameters have to be taken into consideration in the design and implementation of the machine tool. A compromise must always be found between greatly varying goals, as is obvious from the following example. Both the roughing and also the fine machining are executed on the machine tool described in the published application cited at the beginning. Roughing is a method in which material is removed from a blank with high metal removing capacity. In contrast, very low feed and higher precision is used in fine machining. This results in different requirements solely in regard to the chucking. However, the type and configuration of the individual tools, as well as their activation, may also vary greatly. If one also wishes to perform a part or all of the cited steps as dry machining, further restrictions in regard to the configuration of the individual axes and tools result because of the special requirements in dry machining for the removal of the hot chips.